Profiler control for die sinking machines



1941-. R. s. ELBERTY, JR 2,263,764

PROFILER CONTROL FOR -DIE SINKING MACHINES Filed March 9, 1938 2 5 5 1INVENTOR Faber! ,iEZb y Jr:

wmizssgs:

Patented Nov. 25,1941

" PROFILEB CONTROL FOB DIE SINKIN MACHINES Robert S. Elberty, In,Waynesboro,'1'a., assignor to Westinghouse Electric &' ManufacturingCompany, East Pittsburgh, Pa., a corporation oi Pennsylvania ApplicationMarch 9, 1938, No. 194,805

Claims. (01. 90-135) My invention relates, generally, to metal workingtools and, more particularly, to a profile! control for die sinkingmachines.

In 'the usual operation of a die sinking machine, the cutting tool movesalternately in a horizontal and a vertical direction, the extent of eachmovement depending upon thedegree of slope of the guide pattern whichcooperates with a tracing mechanism to govern-the reed movement of thecutting tool. It is apparent that each cut taken by av tool socontrolled will be made up of a series of ridges and the ridges willhave to be very small to result in a suriace even approximating a smoothfinished surface.

The object of my invention is to provide a control for a profiler i'ora-die'sinking machine which shall function to increase the cutting speedand, therefore, the production of the machine, and improve the qualityof the surface produced by the machine.

Another object of the invention is to provide a control for a diesinking machine proiller which shall. function to cause the cutting toolto move in the direction of the contour of the guide pattern instead ofin a series or horizontal and vertical movements which are thehorizontal and vertical components of the contour of the guide pattern.

These and other objects and advantages of the invention will be apparentfrom the following detailed description taken in connection with theaccompanying drawings, in, which Figure 1 is a diagrammatic illustrationof a die sinking machine with the profiler control of the preferredembodiment of my invention'applied thereto;

Fig. 2 is a diagrammatic illustration of a modification of the circuitcontrol means conthe slope oi. the guide pattern engaged by the tracingmechanism, governs the speed relations of two motors which drive sungears of two differential mechanisms whose other sun. gears arecontinuously driven at a constant speed. The

differential speed produced in one of these diiferential mechanismsgoverns the horizontal movement of the profiling tool and tracingmechanism and the differential speed oi theother differential mechanismgoverns the vertical movement thereof. Since these horizontal andvertical movements are applied simultaneously to the profiler, thedirection of movement of the profiler will be the resultant of thehorizontal and vertical speeds and will depend upon the relative valuesof these speeds. Provision is also made for manually setting theprofiler for each cut and for reversing the direction of out after eachout has been made.

Referring now to the drawings, the base plate '2 of the die sinkingmachine is provided with guides 4 which cooperate with guideways in amovable plate 8 having an upstanding bracket member 8. The bracketmember 8 is provided with guides Ill which cooperate with slideways in aplate member l2 to permit vertical sliding movement of plate member H'on bracketmemher 8. Plate member I2 is provided with guides l4 whichcooperate with slideways in plate memher It to permit horizontal slidingmovement of plate member It on plate member l2.

A continuously driven motor l8 driving the profiling tool, or cuttingtool, 20 is mounted upon trolled by the tracer for governing thedirection of rotation of the rheostat motor in which dynamic braking isemployed to cause the rheostat motor to stop quickly at itsv adjustedposition; and,

Fig. 3 is a graph showing the relations of the speeds of the constantspeed differential motor and the horizontal and vertical controldifferential motorsat the diflerent angles of slope of the guide pattem.

In carrying out my invention, I provide a continuously'acting profilingtool mounted for horimotors 30 and 46 is transmitted through the zontaland vertical movement and provide a 1 tracing mechanism mounted formovement with the profiling tool to cooperate with a guide pat-' tern.The contact relation of the tracing mechanism with the guide pattern,depending upon 55 and extends through a worm 52 which has an the plateIt. A workpiece 22 is mounted upon a stationary upright bracket 24 in aposition to be worked upon by the profiling tool 20, A guide pattern 26is also mounted upon the bracket 24 and a tracing mechanism 28 ismounted upon plate lt'for cooperation with the guide pattern Acontinuously driven motor 30 is provided for actuating the sun gears 32and 34 of diil'erential mechanisms 38 and 38, respectively. The othersun gears 40 and 42 of difierential mechanisms 36 and 38 are driven bymotors 44 and 45, respectively. The differential movement betweenditl'erential mechanism 38 to the shaft 48 which has screw engagementwith the plate I2 to provide vertical movement of the plate I2 on thebracket 8. Y motors and 44 is transmitted through the difierentialmechanism 36 to a shaft 50 which may be substantially polygonal in crosssection The diiIerential movement between internal cross section whichwill permit longitudinal sliding movement of worm 52 on shaft 56 andwill also permit shaft 56 to rotate worm 52. Endwise movement of worm 52is prevented by brackets 54 which are secured to the plate I2.

I Block member 56 is mounted upon plate I2 and supports a worm gear 58in cooperative relation with the worm 52. A screw member 66 is securedto horizontally movable plate I6 and cooperates with internal threads onthe worm gear 58 so as to cause horizontal movement of the plate I6 whenmotion is transmitted from the difierential mechanism 36 through shaft56, worm 52 and worm gear 58. Thus it is seen that the differentialmovement between motors 36 and produce horizontal movement of thecutting tool 26 and the tracer mechanism 28, and that the differentialmovement between motor 36 and motor 46 causes vertical movement of thecutting tool 26 and the tracing mechanism 28.

The motor 44 has connected in its field circuit a rheostat 62 which hassuch a range of resistance that when the rheostat is varied from oneextreme of its range to another, the motor 44 will be caused to vary itsspeed from a maximum speed above the speed of the motor 36 to a minimumspeed below the speed of the motor 36; the differentiation between thespeed of the motor 36 and the maximum and minimum speeds of motor 44being substantially equal.

Thus it will be seen that the differential between thespeeds of themotors 36 and 44, as

the speed or motor 44 is varied between its extreme maximum and minimumlimits, will produce a horizontal movement of the cutting tool 26 andthe tracer 28 from a maximum speed of movement in one direction to amaximum speed of movement in the opposite direction.

A rheostat 64 comprising circular resistance elements 66 and 68 isprovided, the resistance elements 66 and 68 being selectivelyconnectable in circuit with the field circuit of the motor 46. Thedesign of the rheostats 62 and 64 may be such as to produce any desiredrelation between the resistances of the two rheostats at any position ofthe contact arms of the rheostats. The

relation of the contact arm 16 with the resistance element 66 is suchthat as the contact arm 16 moves clockwise through an arc of 180, theresistance in the field'of motor 46 will be varied from a mediumresistance which is the resistance required to produce a speed of motor46 equal to the speed of motor 44 through a minimum resistance whichwill cause the s eed of motor 46 to be less than that of motor 36 by anamount substantially equal to the difierence between the maximum speedof motor 44 and the speed of motor 36, and to then increase to a mediumresistance such as will increase the speed .of motor 46 to a speed equalto the speed of motor 36.

The resistance element 68 is connected opposite to that of resistanceelement 66 so that within the 180 range of movement of the contact armI6, the resistance of resistance element 68 will vary from a mediumresistance, which will produce a speed of motor 46 equal to the speed ofmotor 96, through a maximum resistance which will cause the speed ofmotor 46 to be greater than the speed of motor 36 by an amountsubstantially equal to the difference between the maximum speed of motor46 and the speed of motor 36, and then to the medium resistance whichwill again decrease the speed of motor 46 to make it equal to the speedof motor 36. The contact arm 16 oi. rheostat 64 and the contact arm 72of rheostat 62 are connected to be actuated by common shaft 14 throughan arc of which is the extreme range of movement of the contact arms toproduce a desired extreme range of variation of the rheostatresistances. Thus it will be seen that the relative speeds of the motors44 and 46 are simultaneously varied by the rotation of the shaft I4 andby the rotation of this shaft 14 the horizontal and vertical componentsof the movement of the cuttingtool 26 and the tracing mechanism 28 maybe varied.

The shaft I4 is connected to reversible motor I6 which drives the shaftin a forward or reverse direction, depending upon which of its fleldcoils I8 and 86 is energized. The selection of the energization of fieldcoils I8 and 86 of motor I6 and, therefore, the direction of rotation ofmotor I6 is accomplished by means of the switch mechanism 82, which iscontrolled. by the tracing mechanism 28. The rod of the tracingmechanism 28 extends slidably through the ball and socket joint 84 andis biased to the position in which it is shown in Fig. 1 by a springmember 86. In this position it will be seen that contact elements 88 and96 are bridged by the movable contact element 92. The movable contactelement 94 is disposed to bridge contact elements 66 and 96 or contactelements I66 and I62 when the arm of the tracer mechanism is deflectedlaterally. It will be further seen that longitudinal deflection of thearm of the tracer mechanism 28 will cause contact element 92 todisengage contact elements 88 and 96 and if this longitudinal deflectionis suflicient the contact elements 96 and I66 will be engaged thereby.

A circuit from the supply conductor X to conductor I 66 comprisingconductor I66, conductor H8, contact element 96, movable contact element92 and contact element 88 is completed when the movable contact element92 is in engagement with contact elements 88 and 96. When the movablecontact element 94 is in engagement with contact elements I66 and I62, acircuit is established between supply conductor X and conductor III)comprising conductor I68, conductor 8 I2. contact element I62, movablecontact element 96 and contact element I 66. When contact element 94 isin engagement with contact elements 96 and 98, a circuit is completedbetween conductor H6 and supply conductor X.

comprising conductor I68, conductor H4, contact element 96, movablecontact element 94, contact element 98 and conductor HE. A circuit iscompleted between conductor I I6 and supply conductor X when the movablecontact element 92 is in contact relation with contact elements 96 andI66 comprising conductor I68, conductor H4, contact element 96, contactelement 92 and contact element I66.

Conductors I66 and H6 are connected to the reversing switch I64 which,in turn, is connected to the field coils I8 and 86 of the motor 76, and"the motor I6 is energized to run in one direction or the other dependingupon which of the conductors I 66 and H6 are connected by the switchingdevice 82 to the supply conductor X and depending upon the position ofthe reversing switch I64. The reversing switch I 64 is selectivelyactuated by relays I 26 and I22 which, in turn, are selectivelyenergized by the directional switch device I24 which is actuated by theadjustable lugs I26 and I36 mounted on the vertically slidable plate I2toreverse the direction of the vertical movement of plate I2 when theplate has reached either of its predetermined limits or verticalmovement. Relays I29 and I22 also govern he position of contact elementsI32 and I84 to se ect the resistance elements 88 and 68, respectively,of the rheostat 94. A manual control means,- of whichooperating knob I36is a part, is provided for positioning the plate 8 on the base plate 2in a direction normal to the plane of movement of the cuttingtool 29 bythe automatic mechanism after each cut is completed by the tool 29. Anysuitable mecha piece 22, respectively, and that the cutting tool hasprogressed from the lower edge of the work piece 22 to the positionshown cutting the contour in the work piece 22 corresponding'to thecontour oi the pattern 26 traversed by the tracing mechanism 28. At thetime that the machine was deenergized it will be seen that hori-' zontalmotion only was being transmitted to the cutting tool 29 since the slopeof the guide pattern where it is engaged by the tracing device 28 hasonly a horizontal component and since the contact arm'12 of the rheostat92 has been moved to the extreme position on the rheostat representingthe minimum resistance in the fieldcircuit of the horizontal motioncontrol motor 44. The vertical motion of the plate I8 was upward as'seen by the position of the selector switch I24 and the relay I29 beingenergized, contact element I82 was in closed circuit position andresistance element 88 was connectedin circuit with the field coil ofvertical movement control motor 48. At this time the contact arm 19 ofrheostat 64 was in a position which would cause motor 48 to run at aspeed equal to the speed of motor 88, thus giving no vertical componentoi! movement.

The conditions obtaining at this time are represented by the point A onthe curve for the forward motion of vertical motion control motor 48 andthe curve of motor 89 and the point A on the curve of horizontal motor44 in the graph of Fig. 3.

It now the contact element I88 is moved to the closed circuit position,motors I8, 89, 44, 48 and 18 will be energized, relay I28 will beenergized to close its contact element I82 and its part of the reversingswitch I94 to properly select the v 3 tact element 92 out of engagementwith contact element "and the movable contact element 94 into'engagementwith contact elements 96 and 98. The circuit of, the field coil I8 ofmotor l8 v having been broken by the movement of contact element 92 outof engagement with contact element 88, the field of the motor 16 will nolonger be energized in such a directionas to cause it to tend to movethe contact arms 19 and 12 of the rheostats 84 and 62 in thecounter-clockwise direction. The contact element 94, however, havingcompleted the'circuit through conductor II. to the field coil 89 ofmotor 16 by engaging the contact elements 98 and 98 will energize thefield coil 89 of motor I6 and will cause the motor to run in such adirection as to move the contact arms I9 and 12 in the clockwisedirection. The v movement of the contact arms I9 and 12 of the rheostats94 and 82 will so alter the field currents of the motors46 and 44 as tochange their relative speeds and thus decrease the rate of horizontalfeed of the cutting tool 29 and thetracing mechanism 28 and increase theupward vertical feed of these elementsa The motor I8- will operate tochange the resistance of rheostats 64 and 82 until its circuit is openedby-the movement of contact element 9.4 out of engagement with contactelements 98 and 98 and this condition will obtain only whenthe.resultant of the components of horizontal and vertical movementimparted to the cutting tool 29 and the tracing mechanism 28 through thedifferential mechanisms has a direction which isthe. same as thedirection of slope at the point B on the guide pattern 26. e As anotherexample of the operation of the device, it may be assumed that theengagement-oi the tracing device 28 at the point C on the pattern hasmoved the tracing device 28 longitudinally to cause the contact element92 to bridge the contact elements 98 and I99. This will energize themotor 18 and will cause it to move the contact arms 19 and -12 clockwiseuntil the-contact arm 12 has moved clockwise through an arc, of 90 andthe contact arm 19 has moved clockwise through an arc of 90?. At thistime the re.- sistancein the field circuit or motor 44 and the speed ofthe motor 44 will correspond to the point D' on the horizontal motorcurve in the graph of Fig. 3 and the resistance in the fleld circuit ofmotor 48 and the speed of motor 48 will have direction-of operation ofthe motor 18 and to select the resistance element 88 for operation inthe fleld'circuit of the motor 48. The motor I8, however, though itsfield circuit is closed by the movable contact element 92 of controlswitch 82, will not be able to rotate since the stop member I48 will beengaged by thecontact arm 12 of rheostat 82 and will prevent therheostat arm 12* from moving further in the direction of decreasingresistance of the rheostat 82. Thus the cutting tool 29 and the tracingmechanism 28 will that the cutting tool 29 and the tracing device 28will have only upward vertical motion at this. time since the speed ofthe horizontal motion control motor 44 is equal to that of the motor 89and the speed of the vertical motion'control motor 48 is a maximumamount above the speed of motor 89. When this condition has beenestablished, the contact engagement of the tracing.

element 28' with the guide pattern 28 will be such as to hold thecontact element 82 between the pairs of contact elements 88 and 99, and88 and Ill, and the contact element 84 in thepode tionshown in Fig. '1.Motor 18 will then cease to rotate and the vertical motion will beimparted to the tracing mechanisxn'2'8 and the cutting tool continue inhorizontal movement to the left until the change in slope of the contourof the guide pattern 28 at approximately the point B deflects thetracing mechanism to move the movable con- "(8 29 until another changein-the slope of the guide pattern 26 so deflects the tracing mechanism28 as to cause it to readjust the relative speeds of the motors 44 and48 to produce the resultant direction of'motion of the cutting. tool 29and the tracing mechanism 28 conforming with the.direction of slope ofthe guide pattern '28.

When the tool has moved vertically a, predetermined amount. the lug I38will engage the switching device I24 to cause it to deenergize relay I26and to energize relay I22, thus selecting the resistance element 66 ofrheostat 64 to be connected in circuit with the field coil of motor 46and reversing the field coils 18 and 60 of motor 16 with respect to thecontrol circuits III6 and III. This will cause the vertical motion ofthe cutting tool 28 to be downward since the speed of the vertical motorand its field resistance will vary according to the reverse curve forthe vertical motor 46 in the graph of Fig. 3. The reversal of theconnections to the field coils 18 and 86 of motor 16 will permit themotor 16 to rotate in the proper directionto vary the resistances ofrheo-' stats 62 and 64- so that the relative speeds of motors 44 and 46may be varied to produce the proper components of vertical andhorizontal,

' shifting of the plate I6 may also be done automatically bymeans-common in this art.

In Fig. 2, I have shownanother embodiment of a control switch to beactuated by the deflection of a tracer mechanism. Referring to Fig. 2,elements 28', 86" and 84 analogous to elements 26,.

86 and 84 have been provided. The tracing element 28' governs theswitching device 82' to control the direction of flow of current fromthe supply conductors X and Y to the rheostat motor 16', which has itsfield coil I44 permanently connected to the supply conductors X and Y.The position of the switch shown in Fig. 2 corresponds Fig. 1 and inthis position a circuit will be completed to cause the motor 16' torotate in one direction. This circuit extends from conductor K throughconductor I46, contact element I48, conductor I50, contact element I52,conductor I54, conductor. I56, the armature of motor 16',

conductor I58, conductor I66, contact element motor 16, conductor I 66,contact element I14, conductor I64 and conductor I86 to the otherconductor Y of the source of supply.

Thus I have provided a control device for the rheostat motor which willselectively control the direction of rotation of the rheostat motor inresponse to the tracing mechanism and will provide dynamic braking forthe rheostat motor when it is deenergized by the control mechanism.

It will be seen that I have provided a control for the profiler orcutting tool of a die sinking machine which will provide simultaneouslycomponents of horizontal and vertical motions of the cutting toolcorresponding to the horizontal and vertical components of the slope ofthe guide pattern at the point where it is engaged by the to theposition of the switch 82 in the device of V I62, conductor I64,contact. element I66 and con- To provide dynamic braking of the motor I6to I bring it to rest very quickly after it is so deenergized, aresistance I10 is connected across the armature to absorb the power inthe armature when it is deenergized and thus to bring it to a quickstop. If now the contour of the guide pattern should be such as todeflect the tracing mechanism laterally, either contact elements I12 andI14 or contact elements I16 and I18 would be moved to closed circuitposition to energize the armature of motor 16 with the opposite polarityto cause it to rotate in the opposite direction. If contact elements I12 and I14 were moved to closed circuit position by the deflection ofthe tracing mechanism 28' a circuit would be established through thearmature of motor 16' extending from conductor X of the source ofsupply, through conductor I86, conductor I82, contact element I12,conductor I56, the armature of tracing mechanism of the machine so thatthe direction of motion of the cutting tool will always he in thedirection of the slope of the guide pattern, thereby to produce anaccurate and smooth contour and to increase the production of themachine.

'In compliance with the requirements of the patent statutes, I haveshown and described herein the preferred embodiments of my invention. Itis understood, however, that the invention is not limited to the preciseconstruction shown and described, but is capable of modification by oneskilled in the art, the embodiments herein shown being merelyillustrative of the principles of my invention.

I claim as my invention:

1. In a system for controlling the movement of a metal working tool, apair of difierential gear trains each having two sun gears and aplanetary gear, means for driving one of the sun gears of eachof saidgear trains at a substantially constant speed, separate motors fordriving the other sun gear of each of said gear trains, means forsimultaneously varying the speed of one of said motors so as to producea range of speeds of the sun gear driven by said one motor from a speedsubstantially above the speed of the other sun gear of the one geartrain to the speed of the said other sun gear and from the speed of saidother sun gear to a speed substantially below the speed of said othersun gear, while varying the speed of the other of said motors so as toproduce a range of speeds of the sun gear driven by said other motorfrom the speed of the other sun gear of the other gear train to a speedsubstantially different from the speed of said other sun gear and fromthe speed substantially .difierent from the speed of said other sun gearto the speed of said other sun gear, means whereby one of said planetarygears imparts vertical motion to the tool, means whereby the other ofsaid planetary gears imparts horizontal motion to the tool, and meansfor selectively governing the action of said means for varying thespeeds of said motors to thereby selectively vary the direction ofmovement of the tool.

2. In a system for controllingthe movement of a metal working tool, apair of diiferential gear trains each having two sun gears and aplanetary gear, means for driving one of the sun gears of each of saidgear trains at a substantially constant speed, separate motors fordriving the other sun gear of each of said gear trains, means forsimultaneously varying the speed of one of said motors so as to producea range of speeds of the sun gear driven by said one motor from a speedsubstantially above the speed of the other other sun gear to a speedsubstantially below the speed of said other sun gear, while varying thespeed of the other of said motors so as to pro-' duce a range of speedsof the sun gear driven by said other motor from the speed of the othersun gear of the other gear train to a speed substantially different fromthe speed of said other the speed of said other sun gear, means wherebyone of said planetary gears imparts vertical motion'to the tool, meanswhereby the other of said planetary gears imparts horizontal motion tothe tool, and means comprising a tracer mechanism cooperating with aguide pattern for selectively controlling the action of said meansforsimultaneously varyingthe speeds'of said motors to therebyselectively vary the directionof movement of the tool in accordance withthe direction of the slope of that part of theguide pattern engaged bysaid tracer mechanism.

3.'In a system for controlling the movement the speed of the other ofsaid motors so as to produce a range of speeds or the sun gear driven bysaid other motor from the speed of the other sun gear of the other geartrain to a speed sub- =sun gear and fromthespeed substantially-differentfrom the speed of said other sun gear to stantially difierent from thespeed of said other sun gear and fromthe speed substantially differentfrom the speed of said other sun gear to the speed of said other sungear, means whereby one. of said planetary gears, imparts vertical.motion to the tool, means whereby the other of said planetary.gearsimparts horizontal motion to the tool, means for selectivelygoverning the action of said means for varying the speeds of said'motorsto thereby selectively vary the direction of movement of the tool, andmeans whereby said diflferent speed is a speed higher than said speed ofsaid sun gear during a predetermined range of motion of the tool andlower than said speed ofsaid sun gear during a predetermined range ofmotion of the tool. a 5. In a system for controlling the movement of ametal working tool, a pair of differential gear of a metal working tool,a pair of difierential gear trains each having two sun gears andaplanetary gear, means for driving one of the sun gears'of each of saidgear trains at a substantially constant speed, separate motors fordriving the other sun gear of each of said gear trains,

' means for simultaneously varying the speed of one of said motors so asto produce a range of speeds of the sun gear driven by said one motorfrom a speed substantially above the speed of the other sun gear of theone gear train to the speed of the said other sun gear and from thespeed of said other sun gear to a speed substantially below the speed ofsaid other sun gear, while varying the speed of the other of said motorsso as to produce a range of speeds of the sun gear driven by said othermotor from the speed of the other sun gear of the other gear train to aspeed substantially different-from the speed of said other sun gear andfrom the speed other sun gear to the speed 01' said other'sun gear,means whereby one of said planetary gears imparts vertical 'motion'tothe tool, means whereby the other of said planetary gears impartshorizontal motion to the too1,'said means for simultaneously varying thespeeds of said sun gear driving motors comprising rheostats in circuitwith the field windings oi said motors, means trains each having twosungears and a planetary I sun gear to a speed substantially below thespeed of said other sun gear, while varying the speed of the other ofsaid motors so as to produce arange of speeds of the sun gear driven bysaid other motor from the speed of the other sun gear of the other geartrain to a speed substantially difierent from the speed of said othersun gear and from the speed substantially different from the speed ofsaid. other sun gear to the speed of substantially different from thespeed of said for simultaneously actuating said rheostats so as toproduce the aforesaid ranges of sun gear speeds, a tracing mechanismmounted for movement with the tool and cooperating with a guide pattern,and means whereby deviation of said tracing mechanism from predeterminedcontact relation with the guide pattern causes selective directionalactuation of said rheostat actuating means.

4. In a system for controlling the movemen of a metal working tool, apair of difierential gear trains each having two sun gears and aplanetary gear, means for driving one of the sun gears of each of saidgear trains at a substantially constant speed, separate motors fordriving the other sun gearof each of said gear trains, means forsimultaneously varying the speed of one of said motors so as to producea range of speeds of the sun gear driven by said-one motor from a speedsubstantially above the speed of the other sun gear of the one geartrain to the speed of said. other sun gear, mean whereby one of saidplanetary gears impartsvertical motion to the tool, means whereby theother of said planetary gears imparts horizontal motion to the toOL'saidmeans for simultaneously varying the speeds of said sun gear drivingmotors comprising rheostats in circuit with, the field windings of saidmotors, a reversible motor for simultaneously actuating said rheostatsin such a manner as to produce the aforesaid ranges of sun gear speeds.a tracing mechanism mounted for movement with the tool and cooperatingwith a guide pattern, and means governed by predetermined deviations ofsaid tracing mechanism from normal contact relation withthe guidepattern for causing the rotation of, and selecting the direction thesaid other sun gear and from the speed of of rotation of saidrheostatmotor.

6. In a system for controlling the movement of a metal working tool, apair of difl'erential gear trains each having two sun gears and aplanetary gear, means for driving one of the sun gears or each of saidgear trains at a substantially constant speed, separate motors fordriving the other sun gear oi. each of said gear trains, means forsimultaneously varying the speed of one ofsaid motors soas to produce arange of speeds of the sun gear driven by said one motor from a speedsubstantially above the speed of the other sun gear or the one geartrain to the speed of thesaid other sun gear and from the speed of saidother sun gear to a speed substantially below the speed of said othersun gear, while varying the speed of the other of said motors so as toproduce a range of speeds of the sun gear driven by said other motorfrom the speed of the other sun gearof the other gear train to a speedsubstantially different from the speed of said other sun gear and fromthe speed substantially difierent from the speed of said other sun gearto the speed of said th Sun gear, means whereby one of said planetagears imparts vertical motion to the tool, means whereby the other ofsaid planetary gears imparts horizontal motion to the tool, said meansfor simultaneously varying the speeds of said sun gear driving motorscomprising" rheostats in circuit with the field windings of said motor,a reversible motor for simultaneously actuating said rheostats in such amanner as to produce the aforesaid ranges of sun gear speeds, a tracingmechanism mounted for movement with the tool and cooperating with aguide pattern, and means governed by predetermined deviations of saidtracing mechanism from normal contact relation with the guide patternfor causing the rotation of and selecting the direction of rotation ofsaid rheostat motor, said motor having dynamic braking means effectiveonly while pattern, means providing a common mounting for the tool andsaid tracing mechanism, means for imparting to said mounting meansmotions in two different directions simultaneously, and means controlledby said tracing mechanism for varying the relative speeds of the motionsin said two directions in accordance with the components, in said twodirections, of the slope of said guide pattern, said tracing mechanismcomprising a stem element having a contacting portion trolled by saidtracer mechanism comprising two control circuits, means wherebypredetermined forward movement of said stem energizes one of ber and aguide pattern, a variable resistor associated with each of the motorsfor controlling the speed of their associated motors, a reversible drivemotor for said variable resistors, and means whereby deviation of thetracing member from apredetermined control relation with the surface ofthe guide pattern so controls the direction of rotation of said variableresistor drive motor as to produce positioning motor speeds proportionalto the components, in two directions, of the slope of the guide patternat the positional; which the tracing member engages the guide pattern.

9. In a control system for metal working tool positioning motorscontrolled by a tracing member and a guide pattern, a variable resistorcon- I nected to control the speed of each of the motors, a reversiblemotor connected to actuate said resistors simultaneously said resistorsbeing so arranged as to have their relative resistance values varied byactuation by said reversible motor, and means whereby deviation of thetracing member from a predetermined contact relation with the surface ofthe guide pattern so controls the direction of rotation of saidreversible motor as to vary the positioning motor speeds in accordancewith the variations of the relative values of the components, intwodirections, of the slope of the guide pattern.

I 10. In a control system for metal working tool positioning motorscontrolled by a tracing memher and a guide pattern, a reversible motor,means controlled by said reversible motor for varying the relativespeeds of the positioning motors in accordance with the direction ofoperation motor as to vary the positioning motor speeds in accordancewith the variations of the relative values of the components, in twodirections, of

the slope of the guide pattem.

ROBERT S. ELBERTY. JR.

